The effect of coarse and fine Ti3SiC2 particle reinforcement in aluminum matrix composites

Abstract

Metal matrix composites (MMCs) reinforced by MAX phases are a promising class of advanced materials that exhibit high mechanical strength, wear resistance, and fracture toughness. Compared to MMCs reinforced with conventional ceramic particles, MAX phases do not hinder machinability or electrical and thermal conductivity of the metal matrix. This study investigated the effect of adding 3, 9 and 18 wt% coarse- and fine-sized Ti3SiC2 particles to pure Al. The Ti3SiC2/Al composites were fabricated by spark plasma sintering at a relatively low temperature of 540 °C, preventing the decomposition of the MAX phase and retaining its unique layered structure. It was found that the fine MAX particles hindered the sintering process. A high fraction of fine particles resulted in abundant porosity, weak interfaces and deteriorated mechanical properties. The microstructural analysis revealed a homogenous microstructure with the residual porosity being located mostly at grain boundaries near Ti3SiC2–Al interfaces. In addition, thin oxide layers could be observed at some of the Ti3SiC2–Al interfaces, which can aid in facilitating bonding between Al and Ti3SiC2. The composites with mostly coarse particles exhibited superior mechanical properties. The hardness increased with the addition of MAX particles and was shown to be slightly anisotropic, and the highest bending strength was achieved for the 3 wt% Ti3SiC2/Al. Nanoindentation hardness mapping analysis shed some light on the strengthening mechanism. The results of this study can serve as a basis for further research utilizing MAX-phase particle reinforcements in MMCs.